International Journal of Coal Geology最新文献

{"title":"In loving memory of Deolinda Flores (1958–2025)","authors":"Manuela Marques , Isabel Suárez-Ruiz , Lopo Vasconcelos , Henrique Pinheiro , João Graciano Mendonça Filho","doi":"10.1016/j.coal.2025.104923","DOIUrl":"10.1016/j.coal.2025.104923","url":null,"abstract":"","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"313 ","pages":"Article 104923"},"PeriodicalIF":5.7,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145732135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessment and integration of different methodologies for the characterisation of carbon aromaticity and structure in biochar","authors":"K. Alami Sounni ,&nbsp;M. Camps-Arbestain ,&nbsp;J. Kaal ,&nbsp;C.J. Tighe ,&nbsp;M.M. Titirici ,&nbsp;G. Siavalas","doi":"10.1016/j.coal.2025.104925","DOIUrl":"10.1016/j.coal.2025.104925","url":null,"abstract":"<div><div>Carbon removal permanence refers to the duration over which carbon remains securely stored across various reservoirs without re-entering the atmosphere. Random reflectance (R_o) has been proposed as a proxy for assessing carbon permanence in biochar. In this study, R_o was measured for 25 plant-derived biochars and compared with (i) the molar H/C ratio, (ii) Raman spectroscopy parameters, and (iii) pyrolysis-GC–MS fingerprints. Four of the biochars showed bimodal R_o distributions, indicating two distinct reflectance populations. A strong relationship was found between mean R_o and H/C (r² = 0.88). Biochars with H/C ≤ 0.40 had mean R_o ≥ 2.3 %, with ≥83 % of the 500 measurement points per sample exceeding 2 % (IBR_o2), except one bimodal sample. This sample, despite mean R_o of 3.72 %, and H/C of 0.37, had only 65 % of measurements &gt; IBR_o2. Based on the fraction &gt; IBR_o2, the biochars were grouped as: Class 1: &lt; 50 %; Class 2: 50–80 %; Class 3: ≥ 80 %. For unimodal biochars, these classes corresponded to mean R_o &lt; 2.0 %, 2.0–2.3 %, and ≥ 2.3 %, and H/C ≥ 0.45, 0.40–0.45, and ≤ 0.40, respectively. Among Raman parameters, saddle intensity effectively distinguished the classes. Mean R_o inversely related to analytical pyrolysis yield (r² = 0.72). Chemical markers (methoxyphenols and (alkyl)phenols) helped explain transitions between classes. The strong correspondence between mean R_o and H/C in unimodal biochars suggests either proxy may suffice in most cases. However, the fraction &gt; IBR_o2 becomes critical for polymodal, Class 2, non-plant feedstock biochars, or when required by certification registries.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"313 ","pages":"Article 104925"},"PeriodicalIF":5.7,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145732129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in optical properties and morphology of anthracites oxidized under different conditions: In HNO3, air and plasma oxygen","authors":"Sławomira Pusz ,&nbsp;Anna Hercog ,&nbsp;Karolina Olszowska","doi":"10.1016/j.coal.2025.104926","DOIUrl":"10.1016/j.coal.2025.104926","url":null,"abstract":"<div><div>Anthracites, due to their highly ordered internal structure, are chemically quite inert and thus difficult to process. However, for various applications of anthracites, including as precursors of carbon materials with specific properties, improving their processability is often necessary. For this purpose, various pretreatments are used, among which oxidation methods are of great importance. This work aimed to study the influence of oxidation using three different methods (in concentrated HNO₃, in air at 420 °C, in plasma oxygen) on optical properties and morphology of three anthracites of increasing rank (VIC &lt; MO &lt; DON) from the Lower Silesian Coal Basin and Upper Silesian Coal Basin (Poland) and from Donbass (Ukraine), respectively. Scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS), Raman spectroscopy, and light microscopy (imaging and reflectance measurement) allow for following the changes in morphology and optical properties of anthracites after oxidation. In the case of the highest rank DON anthracite, its morphology and optical properties remained almost unchanged following oxidation by all the methods used, except for the narrow oxidation zone created by HNO₃. In the case of lower rank anthracites, MO and VIC, their morphology and optical properties changed significantly under oxidation in HNO₃ and air, but remained unchanged after plasma oxidation. The extent and intensity of the oxidation process were stronger for VIC anthracite than for MO.</div><div>Ultimately, it was shown that the level of anthracite oxidation in HNO₃ and thermal oxidation with air strongly depends on the rank of the anthracite. The nature of the changes in morphology and reflectance parameters also suggests that the liquid agent, HNO₃, acts more intensively but also more closely at the surface of anthracite grains, as it has a lower ability to penetrate deeper into the grains than air. The oxidation level under the influence of oxygen plasma was similar for all anthracites, regardless of their rank.</div><div>Optical properties are very sensitive indicators, which can reveal even very subtle structural changes in anthracites during oxidation, invisible to other research methods. The nature and intensity of changes of optical properties illustrate the extent and level of anthracites' oxidation and can be a useful complement to the results obtained using other research methods for determining anthracites' structural transformations. Due to the growing interest in using anthracite as a potential source of new carbon materials, thorough knowledge of their structural changes resulting from various technological processes, including oxidation, seems to be important from a scientific as well as technological point of view.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"313 ","pages":"Article 104926"},"PeriodicalIF":5.7,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145753508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sweet spot development in heterogeneous shales of lower Silurian","authors":"Yujie Yuan ,&nbsp;Songtao Wu ,&nbsp;Emad Al-Khdheeawi ,&nbsp;Zihao Lin ,&nbsp;Jun Wang ,&nbsp;Menglei Wang ,&nbsp;Yuhan Zhou ,&nbsp;Lai-Chang Zhang ,&nbsp;Zhuo Feng","doi":"10.1016/j.coal.2025.104902","DOIUrl":"10.1016/j.coal.2025.104902","url":null,"abstract":"<div><div>The identification of sweet spots in shale is crucial for ensuring energy security and the economic development of gas resources. However, the pronounced heterogeneity of laminae and lithofacies presents substantial challenges in the accurate identification of sweet spots, particularly in shale formations deposited across the Early Silurian, which was significantly affected by episodic volcanism. To achieve a high-resolution understanding of sweet spot development and accurately identify the economic intervals, this study conducted an integrated analysis of continuous borehole core samples mostly from the Longmaxi Formation. This involved high-resolution lithological, mineralogical, petrophysical, and geochemical characterizations, combined with in-situ gas content measurements. The results establish lamina-scale criteria for sweet spot identification, emphasizing the critical role of fine-scale heterogeneity. Our findings demonstrate that sweet spot development during the Early Silurian is strongly governed by the architecture of laminae and lithofacies, which significantly influence reservoir quality. Based on the proposed criteria, the optimal sweet spot interval (Class I) was identified in the lower Longmaxi Formation, specifically within the integrated sublayer of ‘upper Long-1₁² + Long-1₁³’. This interval is characterized by interbedded thick silty-thin muddy laminae and organic matter (OM)-rich mixed shale (ORMS). It exhibits the highest total organic carbon (TOC), excellent petrophysical and mechanical properties, well-developed nanopore systems, and the highest in-situ gas content. Additionally, Class II and III sweet spots were identified in the Long-1₁⁴ and the integrated ‘Long-1₁¹ + upper Long-1₁²’ sublayers, respectively. These intervals experienced a less intensive volcanism, exhibiting comparable laminae configurations and dominated by OM-moderate siliceous and mixed shale lithofacies, resulting in favorable reservoir quality and gas content, albeit relatively inferior compared to Class I. In contrast, no sweet spots are observed in the Long-1₂ and Long-2 intervals of the upper Longmaxi Formation, with trace volcanism evidence. These intervals are dominated by thick massive, muddy laminae and OM-poor argillaceous shale lithofacies and exhibit poor petrophysical and mechanical properties with low gas content. This study underscores the importance of laminae and lithofacies in heterogeneous shales and the controlling mechanisms of sweet spot development. The findings provide a scientific basis for more accurate resource evaluation and exploitation of shale gas resources.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"313 ","pages":"Article 104902"},"PeriodicalIF":5.7,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145553671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"OM-hosted pore systems in Ordovician Wufeng–Silurian Longmaxi shales in Sichuan Basin SW China: Origin, gas storage, and flow behavior","authors":"Yong Ma ,&nbsp;Omid H. Ardakani ,&nbsp;Dahua Li ,&nbsp;Jianbin Ma ,&nbsp;Ningning Zhong ,&nbsp;Haiping Huang","doi":"10.1016/j.coal.2025.104897","DOIUrl":"10.1016/j.coal.2025.104897","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This study provides an extensive investigation of the origin, morphological evolution, pore structure, and flow behavior of organic matter (OM)-hosted pore systems in the overmature Wufeng–Longmaxi (W–L) shales of the Sichuan Basin, SW China, with implications for shale gas storage and production. Eleven core samples from the Wufeng and Longmaxi formations, spanning a wide range of total organic carbon (TOC) content (0.47–5.48 wt%) but consistently high thermal maturity (EqVRo 3.89–4.20 %), were analyzed using a combination of geochemical analyses, optical microscopy, high-resolution scanning electron microscopy (SEM), three-dimensional focused ion beam-SEM (FIB-SEM) reconstructions, energy dispersive spectroscopy (EDS), and Navier–Stokes-based pore-scale permeability simulations. The OM assemblage comprises pyrobitumen, alginite, graptolites, and fecal pellets, each contributing distinct pore-forming pathways controlled by original ultrastructure, depositional redox conditions, and subsequent diagenetic mineralization. Alginite preserves sponge-like cellular ultrastructures, yielding highly connected macropore networks (&gt; 50 nm), with the highest porosity (&gt; 10 %) and permeability (&gt; 15 μD), representing the most efficient storage and flow pathways. Pyrobitumen develops irregular shrinkage pores and microfracture networks during thermal cracking, producing moderate porosity (4–13 %) and permeability (∼ 0.75 μD), with framboidal pyrite stabilizing pore structures against compaction. Fecal pellets, stabilized by early phosphatization through apatite and fluorapatite precipitation, retain isotropic nanoporous frameworks (40–160 nm) with consistent porosity (∼ 5 %) and permeability (∼ 0.8 μD). In contrast, graptolites display poorly connected cortical fibril-aligned nanometer-sized pores (&lt; 20 nm), contributing minimally to storage (porosity &lt;0.6 %) and permeability (&lt; 0.35 μD). Pore size distribution analysis reveals that alginite and pyrobitumen host the largest connected pores, whereas graptolites and fecal pellets are dominated by isolated, ultrafine structures. Diagenetic mineralization emerges as a critical factor in pore preservation, with apatite and pyrite reinforcing nanoporous networks against mechanical collapse. Furthermore, depositional conditions such as water column stratification, nutrient influx, microbial restructuring, and limited degradation of fecal aggregates facilitated OM preservation, leading to the formation of stable nanoporosity critical for long-term gas storage and migration. Integrated FIB-SEM reconstructions and flow simulations establish a hierarchical permeability ranking of alginite &gt; pyrobitumen ≈ fecal pellets &gt; &gt; graptolites, underscoring the significant role of OM type and diagenetic evolution governing shale reservoir quality. These findings highlight that OM composition and its diagenetic trajectory, rather than TOC or maturity alone, are the primary controls on pore netw","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"312 ","pages":"Article 104897"},"PeriodicalIF":5.7,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145435064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Source of biodegraded oil seep and bitumen rock-impregnations from the Sicilian Orogen and Foreland (Italy): Rock-Eval 6/7S and GC-MS approach","authors":"Ádám Nádudvari ,&nbsp;Rosanna Maniscalco ,&nbsp;Martina Forzese ,&nbsp;Dorota Staneczek ,&nbsp;Dariusz Więcław ,&nbsp;Giovanni Silvio Cassarino ,&nbsp;Ewa Szram ,&nbsp;Leszek Marynowski","doi":"10.1016/j.coal.2025.104900","DOIUrl":"10.1016/j.coal.2025.104900","url":null,"abstract":"<div><div>Hydrocarbons have been known in Sicily for centuries from oil seeps and bitumen-impregnated limestones, which were exploited in the 19^th and early 20^th centuries. In the 1950s, several shallow wells were drilled in the Sicilian Foreland with the aim of hydrocarbon production. The study focuses on oil and bitumen seeps in Sicily, southern Italy. The oil seeps occur on the surface in Madonna dell’Olio (MA) in the Madonie Mountains in northern Sicily. They are also present as bitumen-impregnated porous carbonates in the Ragusa Formation on outcrops and in the subsurface in the Hyblean Foreland in southeastern Sicily (Streppenosa, Castelluccio, and Tabuna mines). Oil seeps introduce hydrocarbons into the natural environment, where biodegradation occurs. As biodegradation increases, the organic sulfur content increases, while the proportion of pyrolytic organic sulfur within total organic sulfur decreases. The Rock-Eval’s Multi-Heating Rates method shows that the Ragusa bitumen is dominated by the heavy fraction, in contrast to the diesel oil dominance of MA. Distinct oil families represent individual sources: carbonates in the Sicilian Fold-and-Thrust Belt, and shales and carbonates in the Ragusa Hyblean foreland. The distribution of biomarkers indicates an early oil window for both the MA and Ragusa fluids, with MA hydrocarbons slightly more mature than Ragusa ones.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"312 ","pages":"Article 104900"},"PeriodicalIF":5.7,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145478232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrothermal enrichment of rare earth elements in Carboniferous–Permian coal-measure kaolins in the Datong Coalfield, North China, linked to Paleo-Asian Ocean evolution","authors":"Shuai Zhang,&nbsp;Yong Ding,&nbsp;Xiliang Zhang,&nbsp;Zhengguo Hu,&nbsp;Qinfu Liu","doi":"10.1016/j.coal.2025.104912","DOIUrl":"10.1016/j.coal.2025.104912","url":null,"abstract":"<div><div>Carboniferous–Permian coals in North China are widely recognized for their enrichment in critical metals, yet the enrichment within their adjacent rocks has received comparatively less attention. Recent investigations have identified rare earth elements and yttrium (REY)-enriched coal-measure kaolins, occurring as partings and floor of coal seams in the southeastern Datong Coalfield. These REY anomalies are of economic interest for potential recovery during kaolin utilization. This study integrates petrological, mineralogical, geochemical, and isotopic geochronological analyses with sequential chemical extraction to determine the origin of the kaolins, the modes of REY occurrence, and their enrichment mechanisms. Zircon U-Pb dating reveals a dominant age peak at ∼300 Ma, consistent with the depositional age of the coal seams. This, together with the presence of volcanic quartz and well-developed columnar/tabular and vermicular kaolinite, indicates a genesis from altered volcanic ash. Zircon geochemistry further suggests that the volcanic ash was derived from continental arc volcanism linked to the southward subduction of the Paleo-Asian Ocean (PAO) beneath the North China Craton (NCC) during the Late Paleozoic. The REY are predominantly hosted in epigenetic siderite and ankerite of hydrothermal origin and in hydrothermally altered kaolinite. Carbon and oxygen isotopic compositions, together with the trace element assemblages enriched in the carbonates, indicate that the hydrothermal fluids were derived from carbonatitic magmas. These magmas formed by partial melting of an enriched mantle that had been metasomatized by carbonate-rich fluids released during dehydration of the subducted PAO slab and its associated sediments. Following PAO closure, the northern NCC transitioned into an extensional tectonic regime during the Middle to Late Triassic. Asthenospheric upwelling triggered partial melting of the metasomatized mantle, generating carbonatitic magmas that intruded along lithosphere-scale faults at the eastern margin of the Datong Coalfield. The evolved hydrothermal fluids infiltrated the coarse-grained coal-measure kaolins and reacted with kaolinite to form carbonate minerals via replacement. The REY and other elements transported by these fluids were incorporated into the crystallizing carbonates and captured by hydrothermally altered kaolinite.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"312 ","pages":"Article 104912"},"PeriodicalIF":5.7,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145593672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Raman spectroscopy of electrostatically isolated organic matter for thermal maturity assessment: A case study on the Mowry Shale","authors":"Tarek Ismail,&nbsp;Soheil Saraji","doi":"10.1016/j.coal.2025.104910","DOIUrl":"10.1016/j.coal.2025.104910","url":null,"abstract":"<div><div>Organic Matter (OM) thermal maturity plays a critical role in hydrocarbon generation within unconventional systems, controlling the transformation of kerogen to oil, and from oil to gas/condensate, thereby defining the fluid type in place. Reliable maturity evaluation underpins resource assessment, sweet-spot mapping, landing-zone selection, and calibration across geochemical, petrographic, and spectroscopic proxies. This study evaluates the thermal maturity of the Mowry Shale in the Powder River Basin using pyrolysis, vitrinite reflectance, and Raman spectroscopy, with emphasis on the impact of sample preparation. Three sample preparation approaches (powdered rock, polished kerogen concentrates, and electrostatically isolated organic-matter) were tested and compared. The novel electrostatic isolation technique separates organic matter from the surrounding mineral matrix, effectively exposing and concentrating it for analysis and substantially improving Raman spectral quality by reducing background noise and mineral interference. Raman parameters derived from electrostatically isolated OM showed a strong correlation between Raman Band Separation (RBS) and VRo-equivalent (R² = 0.85). This approach facilitates rapid and reliable OM identification with reduced preparation compared to conventional methods; however, its broader applicability to other formations needs further investigation. Furthermore, organic petrography provided a formation-specific calibration between Vitrinite Reflectance (VRo) and thermal maturity (Tmax), which enabled extension of VRo equivalency across the full dataset (39 samples) despite direct VRo measurements being available for only 16 samples.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"312 ","pages":"Article 104910"},"PeriodicalIF":5.7,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of lanthanides and yttrium in Chinese coal: Content, distribution, and recovery priority","authors":"Yunfei Li ,&nbsp;Chuncai Zhou ,&nbsp;Chen Li ,&nbsp;Feng Wang ,&nbsp;Shuheng Hu ,&nbsp;Wentao Wu ,&nbsp;Guijian Liu","doi":"10.1016/j.coal.2025.104901","DOIUrl":"10.1016/j.coal.2025.104901","url":null,"abstract":"<div><div>The rapid expansion of the new energy industry has resulted in a significant shift in the demand structure for specific lanthanides and yttrium (REY) and an overall increase in demand, thereby accelerating the depletion of conventional sources and driving the exploration of unconventional sources such as coal-based resources. This study established a comprehensive database of REY in Chinese coal, calculated the average REY content across the nation and various provinces using recoverable reserves, and classified recovery priorities accordingly. The results indicate that the average REY content in Chinese coal is 127.8 ppm, with significant regional variations: the highest contents are found in Shanxi, Qinghai, and the southwestern provinces. Coal-forming ages also influence REY resources potential, with late Carboniferous-early Permian (C₂-P₁) exhibiting the highest levels, followed by a gradual decline over ages until a minor rebound in the Paleogene to Neogene (E-N). Additionally, REY in coal exhibits both inorganic and organic affinities, with phosphorus-containing substances having the most substantial impact. Given the high potential for REY recovery and the considerable content of high supply risk rare earth elements (Pr, Nd, Gd, Tb, Dy, and Y in this work) in Guangxi and Chongqing, these regions are categorized as extremely high-priority areas.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"312 ","pages":"Article 104901"},"PeriodicalIF":5.7,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145491993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enrichment characteristics, volatilization properties, speciation transformation, and environmental implications of trace elements during coal combustion from Huaibei Coalfield, Anhui, China","authors":"Mengfei Lu,&nbsp;Ruijia Liu,&nbsp;Minglian Shen,&nbsp;Guijian Liu,&nbsp;Hao Hu,&nbsp;Zongfan Xie,&nbsp;Zhen Yue","doi":"10.1016/j.coal.2025.104911","DOIUrl":"10.1016/j.coal.2025.104911","url":null,"abstract":"<div><div>The behavior of trace elements (TEs) during coal combustion is highly temperature-dependent, presenting a dual challenge of environmental risk and resource potential. However, the strategic utilization and effective pollution control of coal ash are hindered by insufficient understanding of how combustion temperature differentially governs the fate of critical and harmful elements. Combining combustion experiments with thermodynamic simulations, this study systematically investigated the impact of temperature (400–1100 °C) on the enrichment, volatilization, and speciation transformation of selected critical (Li, V, Ga, Ge, Zr, and Mo) and harmful elements (Cr, Ni, Cu, Zn, Cd, and Pb) in Huaibei coal, and evaluated their distinct environmental implications. The results show that the elements Li, Ga, Zr and Pb are all slightly enriched or enriched in five coal samples, and their contents in coal ashes are on average more than twice those in raw coals, and up to more than four times. The decomposition of organic matter is completed at 500/600 °C, and kaolinite-quartz-muscovite in the raw coal transform into mullite-quartz in coal ash. Trace elements are mainly stabilized as sulfate (Li, V, Cr, Ni, Cu, Zn, Cd, and Pb) at low temperatures, and partially volatilized as gaseous hydroxides (Li, Ga, Mo, Cr, Ni, Cu, Zn, and Cd) with increasing temperatures, or exist as metal oxides in coal ash (Li, V, Ga, Ge, Zr, Cr, Cu, Zn, and Pb). Principal component analysis (PCA) reveals differential responses of TEs to progressive temperature increases. The generally lower volatility of critical elements compared to harmful elements in coal ash leads to their higher retention, highlighting their potential for resource recovery and the consequent positive environmental benefits. However, the presence of harmful elements in ash also causes tangible negative environmental effects, primarily manifested as increased potential ecological risks with increasing temperatures. Cadmium is identified as the dominant risk contributor capable of reaching high risk levels at elevated temperatures. This study provides scientific basis for the harmless utilization of coal ash resources through temperature regulation.</div></div>","PeriodicalId":13864,"journal":{"name":"International Journal of Coal Geology","volume":"312 ","pages":"Article 104911"},"PeriodicalIF":5.7,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145560220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}